public class Main {
    public static void main(String[] args) {
        String s1,s2,t1="ABCDabcd";
        s1=t1.toUpperCase();
        s2=t1.toLowerCase();
        System.out.println(s1);
        System.out.println(s2);
        String s3= s1.concat(s2);
        System.out.println(s3);

     
    }
}